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jamit
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[*] posted on 17-2-2011 at 22:03
solvent distillation


if there is a post on this subject I would appreciate it if someone would direct me to it.

I wanted to know if there's anyone out there who have purified their otc solvents via distillation. Solvents like toluene, denatured alcohol, acetone, xylene, and methyl ethyl ketone.

From my reading on this board and other forums, many solvents that you buy at home depot or hardware stores have unknown impurities added. I want to remove these impurities and so before doing it I wanted to know if there are any tips or suggestions you might have for me.

I would like to hear from those who have actually done the experiment in purifying solvents. thanks in advance.
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Contrabasso
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[*] posted on 18-2-2011 at 11:16


Each distillation needs to be considered separately! Alcohol is denatured to discourage people drinking it tax free. SO the denaturing ingredients are specified to be difficult to separate out.
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Melgar
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[*] posted on 18-2-2011 at 23:22


I've never distilled those solvents. Sure, they can pick up water, although that's doubtful in a metal can, but that's not much of a problem unless you need really dry conditions. And in that case, I dry the solvent over CaCl2. I tend to feel that my bumbling self is more likely to add contaminants than remove them during the process of distillation. :p
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Al Dehyde
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[*] posted on 26-2-2011 at 08:43
Re: solvent purification


Hi Guys, thought this topic would be perfect for my first post, im no expert, i have little experience in organic chemistry and am here to learn and share information, but what type of question is this? there is so much readily available information out there, do a simple google search if you dont have access to textbooks etc i will say- start with research on autoignition temperatures and flash points before you do anything, types of distillations and setups, boiling points, dont consider distillation untill you know the properties and hazards of the compound and the correct distilling method and setup required.

For your reference i have safely distilled/purified/separated otc solvents and obtained anhydrous pure products.
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BromicAcid
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[*] posted on 26-2-2011 at 09:15


Several years ago I decided I would try to distill my 'xylenes' before use. About 80% of the material came over within range, the remainder in the pot darkened to a red / orange oil throughout the course of the distillation that refused to come over even up to 170°C in the pot. What it was I don't know.



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antibody
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[*] posted on 26-2-2011 at 10:11
read up on fractional distillation


http://en.wikipedia.org/wiki/Fractional_distillation

or if the BPs of your solvents have more than 25°C difference, then use simple disitillation, ie no column required
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Nilson
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[*] posted on 2-3-2011 at 14:34


that 25 C difference is not a set in stone difference to go by. It depends on the skill of the chemist, additionally how many times you want to re-distill, and the properties of the chemicals you're trying to separate (azeotropes).

But, I will say it is not a bad thumb-rule to go by :)
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Sedit
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[*] posted on 2-3-2011 at 20:22


I rarely distill any of my OTC solvents unless they contain something I dont want. Right now my favorite is a very large jug that only contains MeOH, DCM and Toluene. It has proven the cheepest MeBn I have found yet so I distill that. Other then that not much else feels worth it. Im starting to question my actions however after seeing Bromicacids post because normally impuritys are not worth my time to be concerned with the form of chemistry I do however 20% is a large number that I would really like to know more about. I think it should be a rule of thumb to atlest distill once to get an idea of what your dealing with then go from there. Im a better preacher then a follower though.;).




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Intergalactic_Captain
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[*] posted on 3-3-2011 at 03:36


The most important thing to consider with OTC solvents is what their primary use is - After that, what manufacturer actually makes them (often the label on the can will show the distributor instead).

Cleaning solvents, like paint-strippers and goo-gone, tend to be combined with various "goos" to decrease their volatility and increase their usability time. As such, these will practically always need to be distilled to be useful.

Pipe-fittings solvents, like those used for PVC, ABS, and CPVC, tend to be mixtures of several solvents and dyes, sometimes plastic fillers. These formulations vary wildly between manufacturers - and end uses. Cleaners and primers for small-diameter pipes tend to contain large amounts of MEK, acetone, and THF, along with dyes and free of filler. The cements for the same pipe usually contain a relatively small amount of filler. For larger diameter pipes, the acetone and THF content tends to lower favoring MEK and larger amounts fillers - You need a longer working time with bigger pipes, hence the lower volatility of your glue/solvent.

Solvents for paints and stains generally tend to be the purest, especially in the professional sector - If you have a Sherwin-Williams store nearby, check their online inventory - You might be surprised by what they carry. Don't be afraid to call up each store - They commonly stock some unusual solvents on the odd chance that someone has a specialty project - I was able to get a gallon of toluene for ~$20USD last year in this way. That aside, these solvents tend to be "cleaner" as their end-use depends on it. They may still be solvent mixtures (xylenes, napththa, "mineral spirits," "lacquer thinner"...), but they don't generally have any high-boiling or polymeric constituents. As extration solvents, they are generally useful as-is.

...On a side note, I not long ago found petroleum (gas, petrol, wherever you are) to be a useful source of "petroleum ether" type solvents. After a few experiments, I was able to repeatably separate 3 distinct fractions - 40-60degC, 60-90degC, and 90-120degC - About 1/3 was the lowest, the other 2 making up about 1/2, and the remainder in the pot being very high-boiling stuff that I never characterized. I was primarily interested in toluene, but as per US regulations, you're likely to never find it. The low-boiling fraction, however, proved to be incredibly useful as a petroleum ether substitute for extractions.




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Arthur Dent
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[*] posted on 3-3-2011 at 04:24


Quote: Originally posted by Intergalactic_Captain  
The most important thing to consider with OTC solvents is what their primary use is - After that, what manufacturer actually makes them (often the label on the can will show the distributor instead).


Thanks for the suggestions, I have been on a quest to gather the most useful solvents in home chemistry at the lowest cost, either by finding inexpensive and unexpected sources, by distilling mixtures of solvents, or by synthetizing them on my own. Of course, those are the most stable solvents, because when I need the really volatile stuff, or stuff that have a very short shelf life, I either make it in-situ or try to find an acceptable substitute.

Quote: Originally posted by Intergalactic_Captain  
...On a side note, I not long ago found petroleum (gas, petrol, wherever you are) to be a useful source of "petroleum ether" type solvents.


Are you talking about gasoline? I've thought often of the goodies that are in the stuff at the pump, but never had the gonads to try to distill the stuff, the thought of a flask filled with gasoline, boiling away on a hotplate, even if all my ground glass is perfectly sealed, scares the crap out of me! :o :o :D

Robert


[Edited on 3-3-2011 by Arthur Dent]




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aonomus
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[*] posted on 3-3-2011 at 04:51


I recently learned that some (not all!) LC grade solvents are produced by taking lower grades of solvent in a reactor with concentrated sulfuric acid (the two must be immiscible), bringing the mixture to reflux with lots of agitation until all the organics are digested out of the solvent and all the water has been pulled out. Then a phase separation followed by distillation in glass cleans up the solvent. That is actually quite scary on the small scale.

Also of note is the fact that the sulfuric acid comes out black or otherwise significantly colored (which might explain some grades of sulfuric acid).
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[*] posted on 31-3-2011 at 15:38


Quote: Originally posted by Sedit  
I rarely distill any of my OTC solvents unless they contain something I dont want. Right now my favorite is a very large jug that only contains MeOH, DCM and Toluene. It has proven the cheepest MeBn

By MeBn did you mean xylene or did you mean toluene (MePh)?

[Edited on 31-3-2011 by jwarr]
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mr.crow
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[*] posted on 2-4-2011 at 15:00


If you think you can distill Toluene out of "lacquer thinner" then its not worth it. I tried washing out the methanol and methyl ethyl ketone with water but distilling only yielded 1/4 the volume of pure toluene.



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[*] posted on 2-4-2011 at 22:32


Quote: Originally posted by BromicAcid  
Several years ago I decided I would try to distill my 'xylenes' before use. About 80% of the material came over within range, the remainder in the pot darkened to a red / orange oil throughout the course of the distillation that refused to come over even up to 170°C in the pot. What it was I don't know.


I saw something like this in a ReactionFactory video where they produced benzene from sodium benzoate and sodium hydroxide.

http://www.youtube.com/watch?v=S8rtyRnZZMU




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overload
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[*] posted on 13-10-2011 at 15:22


The first solvent is DCM bought from ebay and the second is hardware store toluene. Neither of these solvents are acceptable. Fractional distillation is an absolute must before using these solvents in any type of laboratory experiment were maximum purity and yield are desired.

111_1155.JPG - 70kB 111_1156.JPG - 70kB

Even after distilling the DCM bought from ebay I am still left with residue. The residue is less than before and leads me to believe that I may have contaminated it with minerals from the water I used to clean my glassware but there is no way to be certain since I did use distilled water to rinse out any tap water residue. The other possibility is the impurities are being carried over with the dichloromethane. What puzzles me is when I had finished the distillation the DCM was completely clear but once I filled the glass bottle I found a cloudy layer was forming at the bottom. After swirling it around I noticed it looks like actual particles.



[Edited on 14-10-2011 by overload]
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